1. Field of the Invention
The present invention relates generally to aluminum alloys and more particularly, to Al—Zn—Cu—Mg alloys, their methods of manufacture and use, particularly in the aerospace industry.
2. Description of Related Art
A tremendous work has been done during the last decades to improve properties of 7xxx series alloys, and more particularly their strength/toughness balance. U.S. Pat. No. 6,027,582 assigned to Pechiney Rhenalu discloses an Al—Zn—Cu—Mg product with a recrystallization rate not exceeding 35% between quarter-thickness and half-thickness. However microstructure relationships with their fatigue crack growth resistance (FCGR) need still to be clarified.